This PR changes the "configuration" command parameter name from
"datastore_version" to datastore-version. The parameter name has
changed from "datastore_version" to "datastore-version"[1].
The original problem is what I got an error when I try to create
a configuration: "openstack database configuration create: error:
unrecognized arguments: --datastore_version ..."
[1]: a57568397e
Story: 2009960
Task: 44928
Change-Id: I94e02cfd4026c56a05b3acccc3a5327b54e6b585